Cold Definition and 395 Threads

Just got back home from the Kona side of Hawai'i. Wow. What a freakishly cool place that is! Day one, snorkeling. Saw so many fish...blue, yellow, stripes, red, dots, skinny, long, buck-toothed, bug-eyed, orange, green,...wow. Just, wow. Day two, long hike along beach. Admired the flowers...

If you lie on the ground at night with no cover, you get cold rather quickly. Much of this is due to energy loss by radiation. At night in a dry climate, the temperature of the sky can drop to -40oC. If you are lying on the ground with thin clothing that provides little insulation, the surface...

I am coming up with a new wing suit that combines soaring with jet pack propulsion in such a way that even valley dwellers can fly, and possibly commute in this fassion. I fear compressed gas alone will not have enough thrust for long enough. One concept to think of is to charge a...

Can I assume that even though I am a bit of a germ phobe that my body is on a daily basis exposed to cold germs? I try to be careful about keeping my hands clean and not sticking them in the wrong places (mouth, nose, eyes ?). If I am constantly exposed to cold germs and I don't always get a...

"cold shutdown" that doesn't require coolant circulation? I was wondering what is preventing a plant being built that can be truly shut down and not require coolant circulation. Is it that efficiency would be reduced to unacceptable levels?

You now how when you feel a light breeze it feels kind of cool? Why? Atoms are moving faster and they hit your skin with higher velocity so I would think wind would be hotter than normal.

Hello all. Consider the case whereby one brings out a cold drink on a hot day. Why do water droplets form on the surface of the cold glass? I would think that when water molecules in the gaseous state collide with the glass surface, they transfer some energy into the glass. Therefore by the...

If you take it to its extremes and space continues to expand at an accelerated rate, what happens when? 1) space is expanding so fast that virtual particles cannot annihilate. 2) if the space between quarks ends up expanding then the energy needed to pull them apart will spawn new quarks...

Just a quick question relating to thermal equilibrium between a hot and cold body. If a hot body and cold (closed systems) are opened up to each other, the thermal energy will be transfer from the hot body to cold body through conduction. So even when thermal equilibrium is reached, the...

I read that some metals, if sufficiently smooth, will become become cold welded upon contact in a vacuum. What process causes this?

Hi, I've looked everywhere for some advice on this, I hope someone can help. We are making a cooling system for cooling thin films, and part of that setup is a liquid nitrogen-cooled cold finger. This cold finger will be inside an aluminum tube, and will move closer and farther away from the...

I've just set a solar thermal array for research for my thesis. I would like to simulate different usage patterns to see how the system performs. I'm doing this using a Arduino with temperature sensors at the top hot the tank and on the cold supply which will then control a motorised valve which...

Hot water is heavier than cold water. If density is decreasing means its cover area is also increasing, and weight is irrelative to the area body occupies. Isn't it? W=mg, to vary the weight we have to cop with its mass and gravity. As gravity is constant then is it the mass of the water...

Does temperature affect the health benefits provided by drinking tea?

Driving at -30 Celsius versus driving at +25 Celsius. The gasoline has less kinetic energy at -30 Celsius... Yet our cars run fine at -30. You would think that there would be a massive difference because 60 degrees celsius difference (-30 vs +30) is a LOT of kinetic energy. Most...

I've always wished i could figure out how to calculate this. But don't know where to start. scenario: you have to boil a liter of water. if you fill it with cold water from your faucet, it will bill in X amount of time. if you fill the water with hot water from the faucet, it will boil...

I am really not all that intelligent and fairly new to the whole mathematical equation solving thing. So please bare with me, I came to the conclusion instead of reading the daily paper I will read daily articles, as I am reading I am unfamiliar of course with the symbols being undefined in the...

I thought that electrons revolve around the proton faster when the material is hot, and slower if it's cold, if that's not true then from where do the electrons gain the energy to constantly revolve?

Does anyone happen to know any undergrad research programs in the U.S. that deal with cold fusion and related experiments?

I'd like some new material to devour, and I have an interest in this era for some reason, particularly the spy stuff (!) but also the space race, and other associated topics. I don't mind if it's fact or fiction really, it's not an academic pursuit. I'd quite like some books, so I can read them...

In my chemistry class today we learned about equilibrium and how temperature affects the equilibrium constant. An example that was cited was this chemical equation: H2O <--> H3O+ + OH- I learned that increasing the heat of the water will drive the equilibrium toward the right side...

How do these new cold asphalts, that allow to repair potholes filled with water work? What chemistry/mechanism allows them to be so easy to manipulate at normal temperature and then rapidly solidify in a permanent road solution? I am referring to a new kind of cold asphalt, as shown in the...

How do these new cold asphalts, that allow to repair potholes filled with water work? What chemistry/mechanism allows them to be so easy to manipulate at normal temperature and then rapidly solidify in a permanent road solution?

Okay. I'm doing a science fair project on we're kiling the Earth and that changing simple everyday things could help save our dying planet. My experiment is going to be cold fusion vs fossil fuels and to perform that experiment I need to build a simple cold fusion reactor. Anybody got any ideas...

What would be the distinguishing theoretical differences between gravitons with an infinitesimal rest mass (non-zero) and cold dark matter? Reference: Dark matter - Wikipedia Graviton - Wikipedia

I live in the DC metro area and we recently had snow that lasted all day (none stuck to the roads, booo). But I didnt understand that it was still snowing at well above freezing. I have a digital thermometer outside of my window and it read ~41 degrees F at its highest and never dropped below 32...

Like the title, has another cold war begun between China and U.S.. There are some indications and developments or Am I stating the obvious ? http://www.bbc.co.uk/news/science-environment-16423881 Appreciate comments and discussion on the topic.

Hello everyone! I'm into home soapmaking but have no background in chemistry. I read enough about how soap is made so that I largely understand what I'm doing, but lately i got into an argument with a friend about weather or not there is still active lye in soap after ...let's say- two weeks...

Why is better to use the cold water pipe as a ground for electrons?

Stoopid car! Stop blowing cold air :( So, since this is a forum full of people who knows mechanics so I figure this is the perfect place to ask this question! giggle. My car has been a pain in the butt lately. The heater blows cold air until I get the car to go over about 3k rpm. When I say...

Hi, I have a question, why wouldn't this work: Imagine you have a two large parallel plates working as a capacitor with small holes in the center of the two plates. You put a potential over the plates. The electric field is then zero outside of the capacitor. You have Deuterium on one side...

For threading of Power screws ( like in a car jack with square/trapizoidal threading ), why is cold rolling preferred to normal material removal machining ; say turning on lathe. Or is cold rolling even preffered?

I have got a metal plate of aluminium. I want to put compressive residual stresses around the hole in Ansys. Can somebody guide me how can i do in ansys? any help will be appreciated. moazzam habib university of hertfordshire united kingdom

So there have been a few stories about a man named Rossi and his E-cat that can supposedly do cold fusion. My question I have is more business oriented...wouldn't a person that invented such a device prefer to keep the technology underwrap and just sell the energy than actually selling the...

I was reading about cellulose derivatives there and came across the wiki page for methyl cellulose: https://secure.wikimedia.org/wikipedia/en/wiki/Methyl_cellulose which states that it is a hydrophilic compound that dissolves in cold water but not hot water. Up until now, every compound I've...

So, I was reading something today about an Italian Physicist who supposidly was able to make a cold fusion machine. It recently passed an important test and all that crap, and it will be interesting to see where it goes, but I was wondering how exactly cold fusion works? I get the jist of it...

A bottle of coke was taken out of refrigerator. It was then kept in a sensitive weighing balance.Its cap was opened. The initial weight was found to be 2.403 kg. After a while its weight increased to 2.423 kg. Then again it started decreasing. I repeated this experiment for many times. And the...

I'm a freshman in college, and there's a worrying thought that's been growing in the back of my head. Perhaps it's the fact that I've just moved into a strange, new environment where my friends are gone that's making me feel off, but I wonder if I'd really enjoy engineering. I'd say I'm an...

Surprised I only found a couple of messages about Zicam, the Zinc based "cold remedy". http://www.zicam.com/ The idea is that the zinc shortens the life of the cold virus. They don't make any claims like a "cure for the common cold".

Hi guys, I have a few questions for you and I would like to know facts, because as this is a very controversial subject people might feel impelled to answer by opinions. So, What is the real thing behind Cold Fusion? What is the Science behind it? If it really works, how does it...

Any of you ever craved a nice glass of ice cold water? And not after any strenuous physical activity? Because I just did. God, I'm going to kill our brita filter tonight. I hope water isn't fattening.

Homework Statement Why should we check pressure in a tire when the tire is cold? Homework Equations ... The Attempt at a Solution After Googling around, I found a statement saying that when a tire is "cold," it means that it is at 'room' temperature, or the surrounding air in this...

So this last winter, my roommates and I left a bunch of freezy pops outside to get cold fast (the temp was -20F). They were in clear plastic and may have been exposed to the sun. After about a day, we went to pick them up, and they had all turned clear. They stayed clear even when brought...

How are ultra cold temperatures measured? For example, sometimes I see things measured in nanoKelvins. I'm thinking there has to be direct contact since the vacuum is already hotter than this, but how is it actually done?

Was "Defense" a lie during the Cold War? Was "Defense" a lie during the Cold War?

How to transfer "cold" energy instead of heat? My question is pretty basic. I am looking to radiate cold with the same concept of heat dissipation. For example on a peltier thermoelectric module gets hot on one side and cold on the other. A heatsink will help dissipate the heat from the hot...

Hi, guys! (I created the same thread in the Engineering topic nearly a week ago but there has been no response. So I decided to move it here. Thanks.) A few friends and I just had a discussion regarding heat and cold protection in general. Then came across a question of whether it is more...

Hi, guys! First of all, I am no physicist. I am an architect from Vietnam. A few friends and I just had an discussion regarding heat and cold protection in general. Then came across a question of whether it is more difficult and energy consuming for heat protection or for cold protection...

Greetings, I recently joined this forum to get some feedback on this project I'm working and which I have searched for an answer without any luck. My goal is to get the most airflow velocity in an outlet of a ducted fan. I'm using a 20,000RMP fan that is pushing air from a ~1.25" inlet to...

Consider a super cold gas tube (of, say, hydrogen), is the wave function of the gas different than at a higher temperature? How about for a lone electron within the gas?